The canonical Wnt signaling pathway may be the most relevant of the Wnt signaling pathways to the development of cancer. Normal activation of this pathway begins a series of downstream events culminating in the stabilization and increased levels of the protein β-catenin. This protein is normally an inactive cytoplasmic protein, and is found at the cell membrane bound to proteins including E-cadherin. In the absence of Wnt ligand, phosphorylated cytoplasmic β-catenin is normally rapidly degraded. Upon activation of the canonical pathway, unphosphorylated β-catenin is transported to the nucleus where it further results in transcriptional activation of various target genes. The subsequent upregulation in transcription of these target genes leads to changes in the cell, and continuous, unregulated expression of such target genes results in tumor development. Since aberrant Wnt signaling appears to be a necessary precursor in carcinogenesis, effective inhibitors of Wnt signaling are of great interest as cancer therapeutics.